Electrostatic spraying apparatus



May 2, 1967 R. P. FRASER 3,317,138

ELECTROSTATI C SPRAYING APPARATUS Filed Feb. 24, 1964 6 Sheets-Sheet 1COATING MA TEQIAL May 2, 1967 R. P. FRASER 3,317,138

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R. P. FRASER May 2, 1967 6 Sheets-Sheet 6 Filed Feb. 24, 1964 L mm J f II I I I I I I I I f I l\ I I Al Eq I A Eq L United States Patent 63 16Claims. (Cl. 239-1s This application is a continuation-in-part of US.application Ser. No. 285,470, filed June 4, 1963, now Patent No.3,233,831 granted Feb. 8, 1966.

This invention relates to spraying apparatus and more particularly tosuch apparatus for producing a spray of electrostatically chargedmaterial.

There has been developed a portable electrostatic spraying apparatuswhich is rapid in action and highly efficient. One such apparatus isdisclosed, for example, in the above identified application Ser. No.285,470. Apparatus of this type customarily employs a first nozzlethrough which paint or other spraying material is discharged and asecond nozzle supplied with fluid under pressure. The pressurized fluidis discharged from the second nozzle in a helical or vortical patternand atomizes the material emanating from the first nozzle to form thespray. The particles of material are charged to a high electricalpotential and are carried along in the spray toward the object beingcoated through the action of an electrostatic field.

In the use of electrostatic spraying apparatus, it is often desirable tochange from one spray pattern to another while the apparatus is.inoperation, and prior spraying apparatus often proved deficient in thisrespect. example, when coating large exterior surfaces it isadvantageous to use a Wide angle spray, while for smaller objects or incases in which material is to be applied to the interior of a hollowbody it is desirable to employ a narrow angle spray. In addition, inmany types of electrostatic spraying apparatus used heretofore,difficulties have been encountered in providing the optimum particlesize and spray velocity for a given coating operation.

One general object of this invention, therefore, is to provide a new andimproved apparatus for producing a spray of electrostatically chargedmaterial.

More specifically, it is an object of this invention to provide suchapparatus in which the spray is readily adjustable from one spraypattern to another while the apparatus is in operation.

Another object of this invention is to provide apparatus of thecharacter indicated which is capable of producing both a low velocitywide angle spray and a high velocity narrow angle spray.

A further object of the invention is to provide electrostatic sprayingapparatus in which the spraying material is discharge either as asubstantially axial stream, a vortical stream or a combination of thetwo.

A still further object of the invention is to provide electrostaticspraying apparatus which is economical to manufacture and thoroughlyreliable in ope-ration.

In one illustrative embodiment of the invention, the spraying materialis discharged through a first nozzle, while air or other pressurizedfluid is discharged into the path of the spraying material from anannular second nozzle. The first nozzle serves as an electrode which issupplied with a high DC. potential to electrostatically charge theparticles of material. The material and the fluid are fed to nozzlesalong a plurality of flow paths defined by unique conduit means. Theflow path for the fluid is arranged to impart a particular movementthereto such that, upon contact between the fluid and For.

3,317,138 Patented May 2, 1967 ice the spraying material, the materialis directed in accordance with the desired pattern.

In accordance with one feature of certain particularly advantageousembodiments of the invention, the flow path of the pressurized fluid isreadily adjustable to change from one spray pattern to another while theapparatus is in operation. The type of spray is determined by theoperator of the apparatus to produce a pattern which is best suited forthe particular object being sprayed.

In accordance with another feature of the invention, in several goodarrangements, there are provided a pair of flow paths for thepressurized fluid. One of the flow paths is arranged to produce avertical fluid stream, while the other path produces a substantiallyaxial stream. The relative flow of fluid along these paths is controlledin a rapid and straightforward manner such that the spraying materialdischarged from the first nozzle contacts the fluid stream to formeither a vortical spray pattern, a substantially axial spray pattern ora combination of the two.

In accordance with still another feature of the invention, in someembodiments, the flow of pressurized fluid is adjustable to produceeither a low velocity wide angle spray pattern or a high velocity narrowangle spray pattern. Should it be desired to spray, say, a tubularobject, the operator employs the low velocity wide angle pattern to coatthe external surfaces of the object and then adjusts the apparatus toproduce the high velocity narrow angle pattern for coating the internalsurfaces. This adjustment is quickly and easily accomplished without anyinterruption in the ope-ration of the apparatus.

The present invention, as well as further objects and features thereof,will be understood more clearly and fully from the following descriptionof certain preferred embodiments, when read with reference to theaccompanying drawings, in which:

FIGURE 1 is a partially schematic diametric sectional 'view of a portionof an electrostatic spraying apparatus in accordance with oneillustrative embodiment of the invention, with the parts adjusted toproduce a low velocity wide angle spray;

FIGURE 2 is a diametric sectional view, partially broken away, ofportions of the apparatus shown in FIG- URE 1 with the parts adjusted toproduce a'high velocity narrow angle spray;

FIGURE 3 is an enlarged elevational view, partially broken away, of ahand spray gun including the apparatus of FIGURES 1 and 2; and

FIGURES 4, 5 and 6 are partially schematic diametric sectional views ingeneral similar to FIGURE 1 but showing electrostatic spraying apparatusin accordance with three further embodiments of the invention.

Referring to the drawings, and particularly to FIG- URES l and 2, theapparatus comprises an outer body member or housing 1 of insulatingmaterial which is generally in the form of a hollow cylinder. Theforward end of the body member 1 (the right end, as viewed in FIGURES 1and 2) is provided with a dielectric nozzle head 2 which is secured tothe body member by a retaining ring 3. The body member includes screwthreads 4 adjacent its forward peripheral edge to hold the ring inplace.

The outer body member 1 is mounted for limited axial sliding movement ona cylindrical inner body member 5, also of insulating material. Themember 5 includes an axial conduit 7 having a tubular electrode 11therein adjacent the forwardly directed portion 6 of the member 5. Theelectrode 11 is fabricated from semi-conductive material having highelectrical resistivity, and the forward end of the electrode serves as anozzle for the coating material in a manner that will become more fullyapparent hereinafter. The adjacent end of the portion 6 and thesurrounding cap 2 form a nozzle for the pressurized fluid and are spacedapart to define an annular orifice 26. This opening is adjustable bymeans of a shim 27 located behind the cap 2.

An elongated, reciprocably movable pintle 8 is positioned within thepassage 7. The pintle 8 extends through the electrode 11, and itsforward end is provided with a conically flared head 9 which seatsagainst a diverging surface 10 at the adjacent end of the electrode. Thepintle 8 includes a plurality of radially extending fins 12 intermediateits ends which engage the inner wall of the electrode 11 and serve tomaintain the pintle coaxially positioned therein. The rearwardlydirected end of the pintle is connected to an operating rod 25 which iseffective to move the pintle in an axial direction and thereby lift theconical head 9 oif its seat 10.

The non-conductive body member 5 includes a high tension conductor 15.This conductor extends in a direction parallel to the longitudinal axisof the apparatus and terminates in a member 16 of high resistivitymaterial. The member 16 is held in place by an electrically conductivelocking pin 16a in engagement with the electrode 11. The electrode 11 ischarged to a high negative potential from a DC. source 15a through apath which extends from the negative terminal of the source, along theconductor 15, through the member 16 and then along the pin 16a to theelectrode.

The inner body member 5 also is provided with a longitudinally extendingconduit 13 which is supplied with compressed air or other pressurizedfluid. The forward end of this conduit communicates with :an annularchamber 14 between the inner member 5 and the outer body member 1. Aring-shaped member 19 of insulating material is afiixed to the member 5adjacent the nozzle cap 2. The member 19 defines the front wall of thechamber 14 and includes a series of swirl slots 19a, only a portion ofone of the slots 19a being visible in FIG- URES 1 and 2. Each of theseslots extends through the member 19 at an angle with respect to thelongitudinal axis of the apparatus. The outer peripheral surface of themember 19 forms an inclined face 17 which mates with a correspondingseat 18 on the adjacent inner portion of the body member 1. The member19 is held in place on the portion 6 of the 'body member 5 by a lockingring 20 of dielectric material.

The surfaces 17 and 18 form a valve which is movable between a closed(FIGURE 1) position and an open (FIGURE 2) position in response to axialmovement of the outer body member 1 relative to the inner body member 5.In the closed position of this valve, the air or other pressurized fluidin the passage 13 is admitted to the annular nozzle opening 26 along afirst path which extends through the angularly oriented swirl slots 19a.In the open position of the valve, however, the air is led to the nozzleopening 26 along a second path between the surfaces 17 and 18.

The rearwardly directed end of the outer body memher 1 is disposedwithin a sleeve 21 fixedly secured thereto. This sleeve is arranged toslide over the enlarged rearward portion of the inner body member 5 topermit limited movement of the outer body member relative to the innerbody member. Upon movement of the sleeve in a rearward direction, forexample, the outer member 1 and its attached nozzle cap 2 are similarlymoved relative to the inner member 5 to open the valve formed by thesurfaces 17 and 18 and to reduce the size of the nozzle opening 26. Theamount of this relative movement, and hence the size of the opening 26and the annular space between the surfaces 17 and 18 when the valve isin its open position, is determined by the space 22 between the rear endof the outer member 1 and a shoulder 23 on the facing portion of theinner member 5. If desired, the maximum axial dimension of the space 22may be adjusted by means of a shim 24 and in practice may be of theorder of one millimeter or less.

The operation of the apparatus will now be described. When the variousparts are in the positions shown in FIGURE 1, the valve surfaces 17 and18 are in engagement and therefore a gaseous fluid such as compressedair fed through the passage 13 to the annular chamber 14 passes along apath through the inclined swirl slots 19a in the member 19. These slotsproduce rotation of the air to form a vortex which issues from theannular nozzle opening 26. The main air pressure drop is across theinclined swirl slots 19a, and the orientation of these slots in suchthat the axial component of velocity is relatively low and the vorticalvelocity relatively high. At the same time, liquid coating material,such as paint, for example, is fed under pressure into the passage 7.Upon the movement of the operating rod 25 to the right from the positionshown in FIGURE 1, the head 9 of the pintle 8 is spaced from the conicalrecess 10 to permit the liquid to issue from the nozzle orifice in theform of a thin divergent conical sheet. This sheet is coaxial with theaxis of the air vortex and is distributed in the vortex which atomizesthe liquid in accordance with a predetermined spray pattern. Thispattern is such that the liquid is discharged in a low velocity wideangle spray. In several advantageous embodiments, the spray angle 0 lieswithin the range of from seventy degrees to one hundred and fortydegrees and in the illustrated embodiment is about ninety degrees. Inthese embodiments, the velocity of the spray, measured at a distance ofabout one and one-half feet in front of the nozzle, is less than tenfeet per second for best results.

The coating material is electrostatically charged to a high DC.potential during its movement through the high resistivity tube 11. Asthe spray is discharged from the nozzle, an electric field isestablished which produces an attraction between the individual sprayparticles and the object being coated. The arrangement is such that asmooth and uniform coating is formed on the article with minimum wastageof the coating material.

When the apparatus is adjusted to the position shown in FIGURE 2 bysliding the outer body member 1 to the left, as viewed in this figure,relative to the inner body member 5, the valve surfaces 17 and 18 areseparated so that the compressed air passing through the chamber 14 nowbypasses the path formed by the inclined swirl slots 19a and moves alongthe path defined by the surfaces 17 and 18. The thus directed air issuesfrom the narrower annular nozzle orifice 26 as a high velocitynon-vortical stream which initially converges toward the axis of theapparatus. In this mode of operation, there is a comparatively slightpressure drop as the air passes through the gap between the surfaces 17and 18 and a high pressure drop as it passes through the orifice 26. Thecoating liquid issues from around the conical head 9 of the pintle 8 inthe manner previously described. The liquid is discharged as anelectrostatically charged divergent film into the high velocity airstream from the orifice 26 and at substantially ninety degrees to it.The resulting atomization of the liquid forms a comparatively highvelocity narrow angle spray pattern. In certain particularly goodarrangements, the mean velocity of the spray exceeds forty feet persecond at a distance of approximately one and one-half feet in front ofthe nozzle, and the angle 0 of spray ranges between seventeen degreesand forty degrees.

It will thus be seen that the apparatus operates to produce twodifferent spray patterns with two defined ranges of velocity andanglesof projection of the particles of coating material. When theapparatus is operating in the manner described with reference to FIGURE2, the mass of fluid relative to coating material is reduced, and thedrop size of the atomized particles is increased. The increased velocityand increased mass of the particles gives them a greater momentum andenables them to have a greater penetrating effect which is particularlysuitable for spraying small objects or the interior of hollow bodies,for example. The smaller drop size of the wide angle low velocity spraywhich is produced when the apparatus is operating in the manner shown inFIGURE 1 is more suitable for coating external surfaces, particularlythose of comparatively large articles.

Where the apparatus is constructed as a portable hand spray gun, asshown in FIGURE 3, it is preferably provided with two hand grips 28 and29. The grip 28 is the normal butt of the gun and in some respects issimilar to that disclosed in US. application Ser. No. 285,470 referredto above. The other grip 29 is spaced forwardly of the grip "28 and isattached to the sleeve 21. Movement of the grips 28 and 29 toward andaway from each other causes slight axial movement of the sleeve 21 andhence of the outer body member 1 relative to the inner body member 5 toalter the spray pattern of the apparatus. The butt of the gun carries afinger operated trigger 30 which controls the supply of compressed airand coating material to the gun and also the switching of the high D.C.potential.

FIGURE 4 shows a further embodiment of spraying apparatus wherein partscorresponding to generally similar parts in the previously describedembodiment bear the same reference numerals followed by a prime suffix.In the FIGURE 4 arrangement, the inner body member 5 is somewhat shorterthan the body member 5 of FIGURES l and 2 and is provided at' 'itsforward end (the right end, as viewed in FIGURE 4) with an annularnozzle member 31 of high resistivity material. The nozzle 31 isreciprocably supported with respect to the body member 5 and includes anaxial conduit 7' which is flared at its forward end toform a conicalsurface This surface mateswith the head 9' of a pintle 8 slidablypositioned in theconduit 7'. The rearwardly extending end of the conduit7' is of reduced diameter and passes through the adjacent end wall ofthe member 31. A plurality of passages 31a are provided in this endwalland extend in directions substantially parallel to the conduit .7. a

The rear end of the pintle 8 projects through the conduit 7 into anenlarged cavity formed in the facing portion of the body member 5. Thisend of the pintle 8 is provided with a coil spring 32 which normallymaintains the pintle head 9 against its seat 10'. One end of the spring32 is affixed to the rear end of the pintle, while the other end bearsagainst the rearward face of the nozzle member 31 to bias the pintletoward its closed position.

The inner body, member 5' is fixedly secured to the outer body member1', and this latter body member includes a longitudinally extendingconduit 13 which is supplied with compressed air.. The compressed airfed through the conduit 13' flows through one or more orifices 33between-the annular nozzle cap 2' and the retaining ring 3. The axis ofeach of these orifices is tangent to the inner peripheral surface of thecap 2'. The compressed air moving through each orifice is introducedinto an annular cavity 34 formed between this surface and the nozzlemember 31 to produce a vortex which issues from the annular nozzleopening 26.

The liquid coating material is introduced via a tube 36 of rubber orother non-conductive flexible material into the interior of a flexiblebellows-like member 35. The tube 36 is mounted in a longitudinallyextending passage therefor in the inner body member 5', and the forwardend of the tube extends through a radially disposed plate 35a formingtherear end of the member 35. The member 35 encloses the adjacent end ofthe pintle 8' and the coil spring 32, and the end of the member oppositethat including the plate 35a is in fixed relationship with the member31. The interior of the member 35 communicates with the conduit 7'through the passages 31a. A high D.C. voltage is applied to the nozzlemember 31 from a high tension cable 15', a series of resistors 37 and ahelical connector member 38.

The movement of the pintle 8 and the nozzle member 31 is controlled byan axially disposed operating rod 25' which isarranged to bear againstthe plate 35a of the bellows member 35. To initiate the coatingoperation, the operating rod 25' is moved toward the right from theposition shown in FIGURE 4 to contact the plate 35a. This plate in turnbears against the pintle 8' to displace the conical head 9' from thevalve seating 10'. The liquid coating material within the member 35thereupon flows under pressure along a path which extends through theopenings 31a in'the adjacent end of the member 31, along the axialpassage 7 and through the annular orifice around the head of the pintle.The material is electrostatically charged to a high D.C. potential as itemerges from this orifice. Simultaneously with the discharge of thematerial, the vortical air stream produced in the cavity 34 issues fromthe annular nozzle orifice 26'. The liquid is discharged as a thindivergent conical sheet which is distributed in the air vortex toatomize the liquid and produce a comparatively low velocity wide anglespray pattern.

Further movement of the operating rod 25 in the forward direction servesto increase the compression of the coil spring 32 until the forcesexerted by the spring on the nozzle member 31 exceed the frictionalforces tending to restrain relative movement between the nozzle memberand the adjacent cap 2'. The nozzle member 31 is thereupon carriedtoward the cap 2' until it abuts a shoulder 2a on the cap, therebydecreasing the size of the annular nozzle opening 26'. The spacingbetween the shoulder 2a and the forward end of the cap 2' is such thatthe thus adjusted opening 26 produces a more directed atomized spraypattern having a considerably higher velocity and a narrower sprayangle.

FIGURE 5 is illustrative of a further embodiment in which the size ofthe nozzle opening for the pressurized fluid remains constant but whichis otherwise generally constructed in a manner similar in severalrespects to the embodiment of FIGURE 4. As in the FIGURE 4 embodiment,the spraying operation of FIGURE 5 is initiated by movement of theoperating rod 25' toward the right, as viewed in FIGURE 5, to bring therod into engagement with the rear surface of the pintle 8' through theplate 35a. The pressurized fluid within the flexible member 35 flowsthrough the conduits 31a and the axial passage 7" inthe conductivenozzle member 31'' between the pintle head 9" and the flared surface10". The nozzle member 31" is suitably staked to the nozzle cap 2' toprevent relative movement therebetween.

In the FIGURE 5 embodiment, the outer body member 1" is provided Withtwo longitudinally extending air passages 13 and 39. The passage 13" isarranged to feed compressed air or other pressurized fluid through thetangential orifices 33 between the cap :2 and the ring 3' to produce avortex emanating from the nozzle opening 26" in a manner similar to thatdescribed heretofore. The passage 39, however, communicates with anenlarged annular chamber 40 formed in the outer peripheral surface ofthe nozzle member 31". The chamber 40 is connected to the annular cavity34 by longitudinally extending passages 41.

In cases in which it is desired to produce a low velocity wide anglespray pattern, air is fed to the nozzle orifice 26" along a flow pathwhich extends from. the passage 13", through the tangential openings 33and then to the cavity 34 leading to the orifice 26". The sheet of airdischarged from this orifice intersects the stream of coating materialdischarged from the passage 7" to atomize the material and form a lowvelocity wide angle spray.

When it is desired to produce a high velocity narrow angle spray, thesupply of air is transferred to the el0ngated conduit 39 while theapparatus is in operation.

This latter air follows a flow path from the conduit 39, the chamber 40and the passages 41 to the cavity 3 4. The air is discharged from theannular orifice 26" in a nonwortical stream which contacts the coatingmaterial to form the high velocity narrow angle spray. In addition, inseveral good arrangements, the air is simultaneously introduced intoboth the cavity 39 and the cavity 13". The air from the cavity 39"introduces a nonvortical component into the air stream to provide apattern having an intermediate velocity and spray angle. Where theapparatus is constructed as a hand spray gun, for example, the valvesfor controlling the admission of air through the passages 13" and 39illustratively are operated from the butt of the gun.

In several advantageous embodiments, the apparatus is constructed in amanner similar to that shown in FIGURE 5, but the pintle 3' and theoperating rod 25 are eliminated, together with the passage for theflexible tube 36 in the inner body member 5. Thus, as shown in FIGURE 6,for example, an inner body member 5" is substituted for the body member5' of FIG- URE 5 and is provided with an axial flexible tube 36' for thecoating material. The material is fed from the tube 36' through theplate 35a into the bellows-like member 35. The material then passesthrough the conduit 7" in the nozzle member 31" and out the flaredorifice at the forward end of this conduit. The pressurized fluid is ledto the orifice 26' in a manner generally similar to that described abovewith respect to the FIGURE 5 embodiment to produce either a wide anglelow velocity spray pattern or a narrow angle high velocity pattern.

In the various illustrated embodiments of the invention, the changebetween the different spray patterns is accomplished in a rapid andstraightforward manner while the apparatus is in operation to provideadjustable spray patterns which may be varied in accordance with thevarious types of objects being coated. The deposition of the coatingmaterial on the object is further facilitated by the electrostaticattraction established between the object and the individual particlesof material. The generally hemispherical shape of .the forward end ofthe apparatus enhances the disposition of the electrostatic field andfurther improves the coating action.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation, and there is no intention, in the useof such terms and expressions, of excluding any equivalents of thefeatures shown and described, or portions thereof, it being recognizedthat various modifications are possible within the scope of theinvention claimed.

What is claimed is:

1. Electrostatic spraying apparatus comprising, in combination, nozzlemeans defining a discharge orifice conduit, means for directing sprayingmaterial and fluid under pressure to said nozzle means along a pluralityof paths, said conduit means including an axially slidable portion forchanging the flow of said fluid from one of said paths to the other,said spraying material being discharged from said discharge orifice andbeing contacted by said fluid to produce both a wide angle spray patternand a narrow angle spray pattern, a voltage source, means for supplyingvoltage from said source to said nozzle means, to electrostaticallycharge the particles of spraying material directed through said orifice,and means operatively associated with said conduit means for adjustingsaid axially slidable portion, to change the discharge of said materialfrom one of said spray patterns to the other.

2. In a portable electrostatic spray gun, in combination, nozzle meansdefining a discharge orifice, conduit means for directing sprayingmaterial and fluid under pressure to said nozzle means along a pluralityof paths, said conduit means including an axially slidable portion forchanging the flow of said fluid from one of said paths to the other,said spraying material being discharged from said discharge orifice andbeing contacted by said fluid to produce both a low velocity wide anglespray pattern and a high velocity narrow angle spray pattern, a sourceof high DC. voltage, means for supplying voltage from said source tosaid nozzle means, to electrostatically charge the particles of sprayingmaterial directed through said orifice, and means operable during thedischarge of spraying material through said orifice for adjusting theaxially slidable portion of said conduit means, to change the dischargeof said material from one of said spray patterns to the other.

3. In a portable electrostatic spray .gun, in combination, nozzle meansdefining a plurality of discharge orifices, conduit means for directingparticles of spraying material and pressurized fluid to said nozzlemeans and respectively through said orifices, the spraying materialbeing discharged into a stream of said fluid, adjustment meanscooperating with said conduit means for modifying the same to vary theflow of said fluid through the corresponding orifice to produce both avortical spray pattern and a spray pattern in which the individualparticles of spraying material are discharged along substantially linearpaths, a voltage source, means for supplying voltage from said source tosaid nozzle means, to electrostatically charge said spraying material,and means operatively associated with said conduit means for adjust ingsaid adjustment means, to change the path of said spraying material fromone of said spray patterns to the other.

4. Electrostatic spraying apparatus comprising, in combination, meansdefining first and second discharge nozzles in juxtaposed relationshipwith each other, conduit means for respectively directing sprayingmaterial and pressurized fluid to said first and second dischargenozzles along a plurality of paths, said conduit means including anaxially slidable portion for changing the flow of said fluid from one ofsaid paths to the other, the spraying material being discharged fromsaid first discharge nozzle and being contacted by the fluid dischargedfrom said second nozzle to produce both a wide angle spray pattern and anarrow angle spray pattern, a source of high DC. voltage, means forsupplying voltage from said source to said first discharge nozzle, toelectrostatically charge the particles of spraying material directedtherethrough, and means operable during the discharge of sprayingmaterial through said first nozzle for adjusting the axially slidableportion of said conduit means, to change the path of said sprayingmaterial from one of said spray patterns to the other.

5. Electrotatic spraying apparatus of the character set forth in claim4, in which said first discharge nozzle comprises an electrode oftubular configuration electrically connected to said voltage source.

6. Electrostatic spraying apparatus comprising, in combination, meansdefining first and second discharge nozzles in juxtaposed relationshipwith each other, conduit means for respectively directing sprayingmaterial and pressurized fluid through said first and second dischargenozzles, the spraying material being discharge-d into a stream of saidfluid, adjustment means cooperating with said conduit means formodifying the same to vary the flow of said fluid through said seconddischarge nozzle to produce both a vortical spray pattern and asubstantially axial spray pattern, a source of high DC. voltage, meansfor supplying voltage from said source to said first discharge nozzle,to electrostatically charge the particles of spraying material directedtherethrough, and means operatively associated with said conduit meansfor adjusting said adjustment means, to change the path of said materialfrom said vortical spray pattern to said substantially axial spraypattern.

7. Electrostatic spraying apparatus comprising, in combination, meansdefining first and second discharge nozzles in coaxial relationship witheach other, conduit means including a plurality of spraying material andpressurized fluid to said first and second discharge nozzles,respectively, said conduit means having means forming a first portion ofthe flow path for said pressurized fluid for imparting a vorticalmovement thereto and having means forming a second portion of the flowpath for said pressurized fluid for imparting a substantially axialmovement thereto, the pressurized fluid discharged from said secondnozzle acting on the spraying material discharged from said firstnozzle, adjustment means cooperating with said conduit means forcontrolling the flow of fluid along said first portion and said secondportion to produce both a vortical spray pattern and a substantiallyaxial spray pattern, a source of high D.C. voltage, means connectedbetween said source and said first discharge nozzle for applying saidvoltage to the spraying material discharged therefrom, and meansoperable during the discharge of spraying material throughsaid firstnozzle for adjusting said adjustment means to change the flow of fluidthrough said conduit means from said first flow path portion to saidsecond flow path portion, to thereby change the spray pattern of saidmaterial from said vortical pattern to said substantially axial pattern.

8. Electrostatic spraying apparatus comprising, in combination, meansdefining first and second discharge nozzles in coaxial relationship witheach other, conduit means including first, second and thrid flow pathsfor supplying spraying material and pressurized fluid to said first andsecond discharge nozzles, said spraying material being led to said firstdischarge nozzle over the first of said flow paths and said pressurizedfluid being led to said second nozzle over one of said second flow pathand said third flow path, said conduit means having means forming aportion of said second flow path for imparting a vortical movement tothe fluid discharged from said second nozzle and having means forming aportion of said third flow path for imparting a substantiallynonvortical movement to the fluid discharged from said second nozzle,said fluid acting on the spraying material discharged from said firstnozzle to produce a vortical spray pattern in response to movement ofsaid fluid along said second flow path and acting on the dischargematerial to produce a substantially nonvortical spray pattern inresponse to movement of the fluid along said third flow path, a sourceof high D.C. voltage, means connected between said source and said firstdischarge nozzle for applying said voltage to the spraying materialdischarged therefrom, and means operable during the discharge ofspraying material through said first nozzle for changing the flow offluid to said second nozzle from said second flow path to said thirdflow path, to thereby change the spray pattern of said material.

9. Electrostatic spraying apparatus of the character set forth in claim8, in combination, said conduit means including an elongated pintledisposed along said first flow path and having an enlarged end portionin position to block the flow of coating material through said firstdischarge nozzle, and means for moving said pintle relative to saidfirst nozzle to control the flow of material therethrough.

10. Electrostatic spraying apparatus comprising, in combination, aninner body member of generally tubular configuration defining a firstdischarge nozzle, a cylindrical outer body member coaxially supportedaround said inner body member for movement with respect thereto betweentwo positions, a portion of said outer body member being spaced fromsaid inner body member to define a second discharge nozzle, conduitmeans including a plurality of flow paths for supplying sprayingmaterial and pressurized fluid to said first and second dischargenozzles, respectively, said conduit means having means forming a firstportion of the flow path for said pressurized fluid for imparting avortical movement thereto when said outer body member is in one of itspositions flow paths for supplying and having means forming a secondportion of the flow path for said pressurized fluid for imparting asubstantially non-vortical movement thereto when said outer body memberis in the other of its positions, the pressurized fluid discharged fromsaid second nozzle acting on the spraying material discharged from saidfirst nozzle to produce two diflerent spray patterns determined by therelative positions between said body members, a source of high D.C.voltage, means connected between said source and said first dischargenozzle for applying said voltage to the spraying material dischargedtherefrom, and means operable during the discharge of spraying materialthrough said first nozzle for moving said outer body member from saidone position to said other position relative to said inner body memberto change the spray pattern of said material.

11. Electrostatic spraying apparatus of the character set forth in claim10, in combination, one of said spray patterns comprising a low velocitywide angle spray, and the other of said spray patterns comprising a highvelocity narrow angle spray.

12. Electrostatic spraying apparatus of the character set forth in claim11, in combination, said wide angle spray lying within the range of fromabout seventy degrees to about one hundred and forty degrees, and saidnarrow angle spray lying within the range of from about seventeendegrees and about forty degrees.

13. Electrostatic spraying apparatus comprising, in combination, aninner body member including a tubular electrode defining a firstdischarge nozzle, a cylindrical outer body member coaxially supportedaround said inner body member for movement with respect thereto betweentwo relative positions, a portion of said outer body member being spacedfrom said inner body member to define a second discharge nozzle, conduitmeans in at least one of said body members including a plurality of flowpaths for supplying spraying material and pressurized fluid to saiddischarge nozzles, respectively, said conduit means having means forminga first portion of the flow path for said pressurized fluid forimparting a vortical movement thereto when said outer body member is inone of its positions and having means forming a second portion of theflow path for said pressurized fluid for imparting a substantiallynon-vortical movement thereto when said outer body member is in theother of its positions or a substantially non-vortical spray pattern, asource of high D.C. voltage, means connected between said source andsaid tubular electrode for applying said voltage to the materialdischarged from said first nozzle, and means operable during thedischarge of spraying material through said first nozzle for moving saidouter body member relative to said inner body member from said oneposition to said other position, to change the flow of fluid throughsaid second nozzle from said vortical movement to said substantiallynon-vortical movement.

14. Electrostatic spraying apparatus comprising, in combination, aninner body member of generally tubular configuration defining a firstdischarge nozzle, a cylindrical outer body member coaxially supportedaround said inner body member for movement with respect thereto, aportion of said outer body member being spaced from said inner bodymember to define a second discharge nozzle, conduit rneans in at leastone of said body members including first, second and third flow pathsfor supplying spraying material and pressurized fluid to said first andsecond discharge nozzles, said spraying material being led to said firstdischarge nozzle over the first of said flow paths and said pressurizedfluid being led to said second nozzle over one of said second flow pathand said third flow path, said conduit means having means forming aportion of said second flow path for imparting a wide angle spraypattern to the fluid discharged from said second nozzle and having meansforming a portion of said third flow path for imparting a narrow anglespray pattern to the fluid discharged from said second nozzle, said wideangle spray pattern lying within the range of from about seventy degreesto about one hundred and forty degrees and said narrow angle spraypattern lying within the range of from about seventeen degrees and aboutforty degrees, a source of high DC. voltage, means connected betweensaid source and said first discharge nozzle for applying said voltage tothe spraying material discharged therefrom, and means operable duringthe discharge of spraying material through said first nozzle for movingsaid outer body member relative to said inner body member to change theflow of material from one of said pair of flow paths to the other, tothereby change the spray pattern of said material.

15. Electrostatic spraying apparatus of the character set forth in claim14, in combination, the velocity of the wide angle spray being less thanabout ten feet per second, when measured at a distance of about one andonehalf feet from said first discharge nozzle, and the velocity of thenarrow angle spray being in excess of about forty feet per second, whenmeasured at said distance.

16. Electrostatic spraying apparatus of the character set forth in claim14, in combination, said second flow path including a plurality of swirlslots for directing the 12 pressurized fluid moving therethrough along avortica] path.

References Cited by the Examiner UNITED STATES PATENTS 1,401,880 12/1921Connelly 239405 1,531,986 3/1925 Shelburne 239405 X 1,736,768 11/1929Boynton 239-405 X 2,373,595 4/1945 Peeps 239406 X 2,530,206 11/1950Neiburg 239417 X 2,574,879 11/1951 Lundber g et al 239406 2,643,9166/1953 White et al 239-416.5 2,754,225 7/1956 Gfeller 23915 X 2,894,6917/1959 Sedlacsik 239-15 2,904,262 9/1959 Peeps 239-408 3,000,574 9/1961Sedlacsik 23915 3,056,557 10/1962 Walberg 23915 3,059,613 10/1962 Nakaya23915 X 3,219,276 11/1965 Norris 23915 M. HENSON WOOD, JR., PrimaryExaminer. EVERETT W. KIRBY, Examiner. J. D. HUSSER, R. S. STROBEL,Assistant Examiners.

3. IN A PORTABLE ELECTROSTATIC SPRAY GUN, IN COMBINATION, NOZZLE MEANSDEFINING A PLURALITY OF DISCHARGE ORIFICES, CONDUIT MEANS FOR DIRECTINGPARTICLES OF SPRAYING MATERIAL AND PRESSURIZED FLUID TO SAID NOZZLEMEANS AND RESPECTIVELY THROUGH SAID ORIFICES, THE SPRAYING MATERIALBEING DISCHARGED INTO A STREAM OF SAID FLUID, ADJUSTMENT MEANSCOOPERATING WITH SAID CONDUIT MEANS FOR MODIFYING THE SAME TO VARY THEFLOW OF SAID FLUID THROUGH THE CORRESPONDING ORIFICE TO PRODUCE BOTH AVORTICAL SPRAY PATTERN AND A SPRAY PATTERN IN WHICH THE INDIVIDUALPARTICLES OF SPRAYING MATERIAL ARE DISCHARGED ALONG SUBSTANTIALLY LINEARPATHS, A VOLTAGE SOURCE, MEANS FOR SUPPLYING VOLTAGE FROM SAID SOURCE TOSAID NOZZLE MEANS, TO ELECTRO-